In this reign the Alexandrians, for the first time within the records of history, felt the shock of an earthquake. Their naturalists had very fairly supposed that the loose alluvial nature of the soil of the Delta was the reason why earthquakes were unknown in Lower Egypt, and believed that it would always save them from a misfortune which often overthrew cities in other countries. Pliny thought that Egypt had been always free from earthquakes. But this shock was felt by everybody in the city; and Agathias, the Byzantine historian, who, after reading law in the university of Beirut, was finishing his studies at Alexandria, says that it was strong enough to make the inhabitants all run into the street for fear the houses should fall upon them. The reign of Justinian is remarkable for another blow then given to paganism throughout the empire, or at least through those parts of the empire where the emperor's laws were obeyed. [Illustration: 313.jpg A MODERN HOUSE IN THE DELTA AT ROSETTA] Under Justinian the pagan schools were again and from that time forward closed. Isidorus the platonist and Salustius the Cynic were among the learned men of greatest note who then withdrew from Alexandria. Isidorus had been chosen by Marinus as his successor in the platonic chair at Athens, to fill the high post of the platonic successor; but he had left the Athenian school to Zenodotus, a pupil of Proclus, and had removed to Alexandria. Salustius the Cynic was a Syrian, who had removed with Isidorus from Athens to Alexandria. He was virtuous in his morals though jocular in his manners, and as ready in his witty attacks upon the speculative opinions of his brother philosophers as upon the vices of the Alexandrians. These learned men, with Damascius and others from Athens, were kindly received by the Persians, who soon afterwards, when they made a treaty of peace with Justinian, generously bargained that these men, the last teachers of paganism, should be allowed to return home, and pass the rest of their days in quiet.